This invention relates generally to steerable vehicles, and more particularly to a drivable, steerable platform.
Drivable, steerable platforms have been used in industrial and agricultural equipment. Known prior art devices utilize complex mechanical linkages to effectuate steering. The mechanical steering linkages are actuated by hydraulic cylinders driven by a selectively actuated hydraulic pump. The wheels can typically be steered through angles greater than 180.degree.. Due to mechanical limitations of the linkage system, however, the wheels cannot be steered through an angle of 360.degree..
Typically, such platforms receive their driving power from an internal combustion engine or an electric motor driven by a battery. The engine or motor drives a hydraulic pump which delivers fluid under pressure to hydraulic motors attached to each wheel of the platform. The hydraulic motors that drive the wheels must be carefully regulated for the wheels to each turn at the same speed.
Other known prior art devices include cable steering systems. Such devices include a plurality of spools on which cable is wound and unwound to effectuate steering. In such systems, the wheels of the vehicle cannot be steered through an angle of 360.degree..
Yet other known prior art devices include wheels powered by an engine through a transmission, pulleys, belts, shafting and gearing assemblies. Sprockets and gear chains may be included to effectuate steering. Hydraulic pumping devices may be used, and the wheels are typically permitted to turn through about 180.degree..
The control apparatus of known prior art devices permits only limited control of vehicle steering and driving. One known prior art remote control lawnmower can be steered only through relatively large angular turns. Another known prior art lawnmower operates only on the principle of random motion within a boundary.
The known prior art devices offer complex mechanical and/or hydraulic construction and relatively poor control over device steering and driving.